What is the shape of American racism? This thorny question received an interesting and extensive look from a recently released study examining the outcomes of a nationwide sample of people between 1989 and 2015. Their life history can help answer this question.

The big headline result was a huge gap in intergenerational mobility between black and white men — but surprisingly, only for men. Black women's mobility was almost exactly the same as white women. One very likely culprit for this difference is America's criminal justice gulag, a vastly disproportionate share of whose victims are black men.

Put together by researchers from Harvard, Stanford, the National Bureau of Economic Research, and the U.S. Census Bureau, the study measured generational mobility by ranking household income, then ranking the children after they grew up and got jobs of their own. It found that black men (and American Indians) had significant downward mobility relative to whites, Hispanics, Asians, and even black women.

The researchers examine and discard several potential explanations for why black women seem to be doing so much better than black men. It's not wages, working hours, or employment rates, all of which are fairly similar to white women from similar income ranks — though one should note there is still a large overall income gap between black and white women because there are a lot more black women further down the income rankings. Black men, by contrast, have a large income gap even compared to white men from a similar household income rank. The fact that blacks marry less does mean more single-earner households, but that only reduces the overall gap somewhat. The researchers conclude that the black-white intergenerational mobility gap really is a peculiarly male-driven phenomenon.

What has to be at least partly responsible, however, is that black men are being vastly disproportionately hassled, beaten, strangled, arrested, or shot by cops; charged more aggressively by prosecutors; and sentenced more severely by judges. It's not hard to figure how jail time or a run-in with the cops might affect one's employability, income, or future earning potential. Indeed, the researchers found an incomprehensible 21 percent of the black men who grew up in the poorest households were incarcerated on any given day in 2010, as compared to just under 7 percent of the corresponding lowest-class white men, or less than 2 percent of the corresponding lowest-class black or white women. (As with mobility, black and white women were almost equally likely to be incarcerated in this measurement.)

The researchers didn't examine American Indian men with the same granularity, but it's probable that group is being treated about as horribly as black men.

One should note that as usual with such measurements, the class bias in the study's incarceration snapshot is gigantic. For both races, the likelihood of incarceration drops sharply and smoothly as parental income increases. Scarcely any of the white men with the richest parents were incarcerated, while "only" about 2 percent of the corresponding high-class black men were — a huge racial bias, but still about a nine-tenths smaller absolute risk than that of the bottom-class black men mentioned above.

This result challenges a popular understanding of the concept of intersectionality that has become a commonplace in the discourse about bigotry. By this view, the various forms of oppression that exist — sexism, racism, homophobia, transphobia, ableism, and so on — only have a positive vector, and can therefore be added up like arithmetic. Muslims suffer religious bigotry, while Muslim women also suffer sexism, so Muslim women are worse off than Muslim men.

In some contexts, that seems to be very true. Transgender women of color, for instance, appear to suffer considerably more violent attacks than white transgender women.

But, as shown by this study, and many others on American mass incarceration, some oppressions do not stack up so simply. Black men, and above all poor ones, are virtually unique in the level of sustained brutality they face at the hands of the criminal justice system.

It is important not to draw some curdled men's rights conclusions from these facts, and start ranting about how women are somehow hogging the spotlight, or that men are the "real victims." Women really do face particular oppression, and toxic masculinity really is a severe problem across the globe. In particular, the finding about black men and prison in no way disputes the fact that sexism and patriarchy exist among black men as they do among white ones.

Instead, we should embrace the fact that oppression is quite textured and nuanced, and that achieving egalitarian liberation for all Americans will require tailored solutions depending on the issue. When it comes to the criminal justice gulag, there is nothing wrong with noting that it is overwhelmingly a male issue, very heavily correlated with poverty, and focusing remedies accordingly. For instance, the researchers found that neighborhoods with lower levels of racial bias, or where fathers were more common, did better in intergenerational terms. Therefore, efforts to help combat bias — in particular the centuries-old racist stereotype of the black man as a hyper-sexualized, unstoppable criminal beast — are worth pursuing, as are criminal justice reforms to reduce the prison population and allow fathers to return to their families. A return to desegregation policy, to prevent blacks from being stuffed into dysfunctional, impoverished ghettos, would also likely help considerably.

Incidentally, that would also greatly assist poor black women, who have their own nuanced set of problems rooted in lack of material resources. But while broad-spectrum remedies are especially compelling, there's also nothing wrong with focusing special attention on black men when they face particularly severe problems. On the contrary, basic justice requires it.